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Applications of Pyridine-Containing Polymers in Organic Chemistry
Published in Dale W. Blackburn, Catalysis of Organic Reactions, 2020
Gerald L. Goe, Charles R. Marston, Eric F. V. Scriven, Edward E. Sowers
DMAP is now preeminent among commercially used catalysts for difficult acylations.15 This has led us to seek a polymeric version of DMAP that would have all the advantages of a heterogeneous catalyst. When we undertook this project several polymeric versions of DMAP had been described. Klotz made the first example by attaching an acid-functionalized dialkylaminopyridine to a polyethyleneimine polymer (Scheme 1).16 He subsequently made many similar functionalized polyimines17 and demonstrated their catalytic ability by kinetic experiments on the hydrolysis of p-nitrophenyl caproate. These polymers suffer from the drawback that the pyridine is attached to the polymer backbone by an amide linkage which is susceptible to scission when, for example, regenerating the resin for reuse using sodium hydroxide.
Polymer-Bound Dialkylaminopyridine Catalysts
Published in John R. Kosak, Thomas A. Johnson, Catalysis of Organic Reactions, 2020
James G. Keay, Eric F. V. Scriven
The superior catalytic abilities of 4-dialkylaminopyridines as acylation catalysts were first demonstrated over 20 years ago [1,2]. Since that time 4-dimethylaminopyridine (DMAP) has emerged as the preferred catalyst for a variety of synthetic transformations under mild conditions, particularly acylations, alkylations, silylations, esterifications, polymerizations, and rearrangements [3]. Its use has been particularly beneficial in the acylation of sterically hindered alcohols where only low conversions are possible under normal conditions [2]. Rate increases of 104 were observed in the benzoylation of 3-chloroaniline for DMAP versus pyridine [4].
Polymeric Matrix Systems for Drug Delivery
Published in Raj K. Keservani, Anil K. Sharma, Rajesh K. Kesharwani, Drug Delivery Approaches and Nanosystems, 2017
Ilić-Stojanović Snežana, Ljubiša Nikolić, Nikolić Vesna, Dušica Ilić, Ivan S. Ristić, Ana Tačić
For the application as drug carrier, poly(lactide) should be defined molecular weight. Thus, catalyst, which can reduce the polymer chain length, and small molecular weight compounds, that can significantly change the properties of PLA, are used in poly(lactide) synthesis (Ristić et al., 2013b). Pyridine, in the form of 4-(dimethylamino) pyridine (DMAP), is used as a catalyst for the regulation of poly(D,L-lactide) chains lengths. The high molecular weight poly(lactide) depolymerize with primary alcohols at 38°C in the solution and at 185°C in the mass. Poly(lactide) with desired molecular weight can be obtained by transesterification.
Tumor microenvironment responsive nanogels as a smart triggered release platform for enhanced intracellular delivery of doxorubicin
Published in Journal of Biomaterials Science, Polymer Edition, 2021
Parveen Kumar, Gautam Behl, Sumeet Kaur, Nalini Yadav, Bo Liu, Aruna Chhikara
Doxorubicin hydrochloride (DOX) (98%) was purchased from carbosynth (UK). Poly(ethylene glycol) monomethyl ether, Mn = 2000 (PEO2000-OH), 2-bromo-2-methylpropionic acid (98%), 3,3-dithiopropionic acid (99%), copper (II) bromide (CuBr2) (99%), glutathione reduced ethyl ester (GSH-OEt) (≥90%), L-ascorbic acid (99%), and sorbitan monooleate (span-80) were purchased from Sigma-Aldrich. DMAEMA (97%) was purchased from Alfa-Aesar and purified by passing through basic alumina to remove the inhibitors. Poly(ethylene glycol) monomethacrylate (PEOMA526, Mn=526 g/mol) was purchased from Sigma-Aldrich and purified according to the procedure reported in the literature [40]. PEG2000-Br macroinitiator, disulfide cross-linker, and tris(2-pyridylmethyl)amine (TPMA) catalyst were synthesized according to the reported procedure with slight modifications (supporting information) [41–43]. 4-dimethylamino pyridine (DMAP) was purchased from Spectrochem (India). 3-(4,5-dimethyl-2-yl)-2,5-diphenyltetrazoliumbromide (MTT) was purchased from Hi-Media (India). 4′,6 diamidino-2-phenylindole (DAPI) was purchased from Santa Cruz Biotechnology (India). All other chemicals used were of analytical reagent quality.